79 
Rock of Gibraltar, and adjacent Country, 
sinter, with numerous stalactites from the roof, and thick, mas- 
sive pillars, as usual in caves of this kind. Many caves foi- 
nierly existed, which are now entirely filled with calc-sinter 
and calc-tuff. Few of these caves are large. St Michael’s 
Cave, about 800 feet above the level of the sea, which is the 
largest and best known, is about 100 feet in length, 40 in 
breadth, and 40 or 50 in height. The stalactites are short and 
thick, and generally of a brown calc-sinter, which is heavier 
and harder than the other varieties. At the farther extremity 
of this cave are many deep hollows ; in some of these I found 
parts of the skeletons of goats, which had no doubt fallen into 
these pits, and being unable to escape, had there perished. 
Bones and skeletons may in this way be often found in these 
caves, encrusted and petrified by the calc-sinter. Below this 
upper cave occurs another smaller cave, but more beautiful, 
into which you descend by rope-ladders by one of these deep 
hollows. Many amusing fables relate to this cave. Hundreds 
of small caves occur in the rock, generally I think situate in 
the conglomerate, and filled in part with calc-sinter and calc- 
tuff. St Michael’s cave, however, occurs in the solid limestone. 
Some of these caves present most picturesque and magnificent 
appearances. The calc-sinter of these caVes, and the calc-tuff 
of the conglomerate limestone appear to have a similar forma- 
tion ; the tuff is associated with the sinter in the caves, the sin- 
ter is associated with the tuff in the rock : if the one, therefore^ 
is gradually forming, so is the other ; if the one is formed by 
percolation of water through the rock, which holds the calcare- 
ous matter in solution, so is the other ; and thus the formation of 
the one is connected with, and illustrates the formation of the 
other. 
To the N.E. of the Bock of Gibraltar, about 15 miles on the 
shores of the Mediterranean, rises a very lofty range, called the 
Apluxara Mountains, steep, massive, and bare. J did not exa- 
mine these hills, but they are probably a continuation of the 
limestone of Gibraltar. The neiitral ground which connects 
Gibraltar with Spain is 2 or 3 miles in length, beyond which 
the country rises into round, sloping hills. The rocks, to 
the distance of 10 or 12 miles to the N. W. of Gibraltar, are 
various kinds of limestone, coarser than the limestone of the 
